New all-solid sulfur-based battery outperforms lithium-ion technology

A new all-solid lithium-sulfur battery developed by an Oak Ridge National Laboratory team led by Chengdu Liang has the potential to reduce cost, increase performance and improve safety compared with existing designs. Credit: Department of Energy's Oak Ridge National Laboratory

(Phys.org) —Scientists at the Department of Energy's Oak Ridge National Laboratory have designed and tested an all-solid lithium-sulfur battery with approximately four times the energy density of conventional lithium-ion technologies that power today's electronics.

"Our approach is a complete change from the current battery concept of two electrodes joined by a liquid electrolyte, which has been used over the last 150 to 200 years," said Chengdu Liang, lead author on the ORNL study published this week in Angewandte Chemie International Edition.

Scientists have been excited about the potential of lithium-sulfur batteries for decades, but long-lasting, large-scale versions for commercial applications have proven elusive. Researchers were stuck with a catch-22 created by the battery's use of liquid electrolytes: On one hand, the liquid helped conduct ions through the battery by allowing lithium polysulfide compounds to dissolve. The downside, however, was that the same dissolution process caused the battery to prematurely break down.

The ORNL team overcame these barriers by first synthesizing a never-before-seen class of sulfur-rich materials that conduct ions as well as the lithium metal oxides conventionally used in the battery's cathode. Liang's team then combined the new sulfur-rich cathode and a lithium anode with a solid electrolyte material, also developed at ORNL, to create an energy-dense, all-solid battery.

The new ionically-conductive cathode enabled the ORNL battery to maintain a capacity of 1200 milliamp-hours (mAh) per gram after 300 charge-discharge cycles at 60 degrees Celsius. For comparison, a traditional lithium-ion battery cathode has an average capacity between 140-170 mAh/g. Because lithium-sulfur batteries deliver about half the voltage of lithium-ion versions, this eight-fold increase in capacity demonstrated in the ORNL battery cathode translates into four times the gravimetric energy density of lithium-ion technologies, explained Liang.

The team's all-solid design also increases battery safety by eliminating flammable liquid electrolytes that can react with lithium metal. Chief among the ORNL battery's other advantages is its use of elemental sulfur, a plentiful industrial byproduct of petroleum processing.

"Sulfur is practically free," Liang said. "Not only does sulfur store much more energy than the transition metal compounds used in lithium-ion battery cathodes, but a lithium-sulfur device could help recycle a waste product into a useful technology."

Although the team's new battery is still in the demonstration stage, Liang and his colleagues hope to see their research move quickly from the laboratory into commercial applications. A patent on the team's design is pending.

"This project represents a synergy between basic science and applied research," Liang said. "We used fundamental research to understand a scientific phenomenon, identified the problem and then created the right material to solve that problem, which led to the success of a device with real-world applications."

More information:
The study is published as "Lithium Polysulfidophosphates: A Family of Lithium-Conducting Sulfur-Rich Compounds for Lithium-Sulfur Batteries," and is available online at dx.doi.org/10.1002/anie.201300680

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42 comments

There are so many new battery advances that I can't keep track of them. And there are numerous technologies that might be viable. The only safe prediction is that the lead-acid battery will be on the way out in 5 or 10 years.

Solid battery tech sounds great. It would be so much easier to stack 50 of them in a 'pile' for 100volts, without the electrolyte leaking around and shorting it all out. The resulting vehicle battery would be far less bulky

Even if it were double cost - at 4 times the energy density it would mean e.g. a doubling of current EV ranges without a change in overall cost of the vehicle. Double the current ranges would be ample to eradicate range anxiety and make EVs useful in most all situations.

The 60C optimal operating range is probably something that still needs to be addressed

It would be so much easier to stack 50 of them in a 'pile' for 100volts, without the electrolyte leaking around and shorting it all out.

There are two unkowns here:1) does the battery hold for more than 300 cycles, and how much more, and for how long?2) does it have similiar under/overvoltage limitations as regular lithium chemistries?

A battery for electric vehicles should last on the order of 2500-5000 cycles to be viable. Then there's the problem of battery management because cells in a stack are limited by the weakest cell. Battery management is more wasteful when the cell voltage is low, because the voltage loss in semiconductors is proportionally higher when the stack voltage is lower, and you can't stack too many cells in a single BMS "module" because of the limiting factor. Ideally, you'd monitor and recharge each cell individually so you don't get differences in the state of charge between cells in series and can utilize the full potential of each.

The 60C optimal operating range is probably something that still needs to be addressed

That was not an "optimal" operating range, but simply the temperature where they tested it. Presumably because elevated temperatures cause faster wear.

Double the current ranges would be ample to eradicate range anxiety and make EVs useful in most all situations.

That depends on what kind of an EV you're talking about. If it's a Tesla Model S with the large battery, then yes. If it's a Nissan Leaf, then no, because doubling the range from 70 miles to 140 miles is not yet enough.

The difference being that the former is way too expensive as it is for normal people to buy, while the latter is just somewhat too expensive after tax rebates. It's what people can reasonably buy that makes the breakthrough or not.

This is also a good point about cheap lithium cells as well. Being cheaply made, they have larger variance in capacity, so when put in a series you have to carefully match the cells to have similiar capacity, and that costs a great deal of money because you have to test each cell in advance.

If you don't match the cells across modules, and match modules across whole battery systems, then you're either running the risk of early battery failure, or you have to take conservative estimates about the available capacity and simply not use the cells to their full extent to account for the weaker links. If even one cell in one module is, say 15% weaker than the rest, then the entire battery has 15% less capacity, so the cells being cheap may not actually give you any cost savings unless you simply don't care that they don't deliver as much as promised.

Not to mention that the cheap cells may also age at different rates, making the battery capacity fall as fast as its worst module's.

At energy densities like this, the applications for electrically powered aircraft begin to look quite viable. Electrically powered aircraft have the advantage of lower vibration than piston engines, and no gearboxes.

The next big question is, of course, how many cycles can these batteries withstand, and how much would it cost to recycle them? Even if we assume that 300 cycles is the limit; it may not be a major issue as long as the batteries themselves can be recycled at low cost.

This is awesome! I like the fact that this has been developed by a government lab. It kind of demonstrates the government does work, and taxpayers are benefiting from the fruits government spending.

Actually, the science behind this is awesome and surprising. I think for EV's it's fantastic. Also as a replacement for small single cycle engines, like lawnmowers, trimmers etc, this kind of energy density could make them very desirable.

It appears that the researchers have taken care of the scientific barriers, now its up to the manufacturers to see if they can efficiently produce these. If they can, these should be the prevailing battery tech that you would see in next gen vehicles, probably 5 to 8 years from now.if an ev has a range of 200km, now its 800 km; thats nothing short of amazing and would abolish the 25 000$+ gas vehicle market (assuming entry electric model starts at 30, 000), so if this doesnt come to market blame the oil companies. Of course you could always buy at 16 000 a huandai...

1) does the battery hold for more than 300 cycles, and how much more, and for how long?A battery for electric vehicles should last on the order of 2500-5000 cycles to be viable.

The correct measure should be: how many kilometers do you get out of one set of abtteries before it neds replacement.If that value is somewhre in the 150k-200k range then that's OK because most cars don't last that long. If the battery holds more charge it doesn't need to be able to support as many recharge cycles. (In an extreme case: if there were a super-battery that could supply the energy for 200k kilometers of driving we wouldn't need to have it be rechargeable at all)

Presumably because elevated temperatures cause faster wear.

This is something I learned reading/writing papers: Anything not explicitly stated in the paper should notbe inferred. I'd wager that the 60C is the optimal temperature for maximizing recharge cycles. They want to show how good the battery is - not how bad.

It is already on the inventor's bench! How can you say that 300 cycles is the limit or that it will need no less than 60°? For now we can only say it is a very interesting concept but, if everything goes well, we have to wait at least some year before we can buy one. About recharging: We know that lithium batteries are very picky about recharging, but why these new batteries should do the same? Just wait and see.

How can you say that 300 cycles is the limit or that it will need no less than 60°?

Point being: That's what they have measured.

So unless someone measures it at different temperatures what this thing needs or how many ccyles it will do under different conditinos is speculation.

For a researcher it's naturally most interesting what the optimal behavior would be. You always want to see how far your invention will go. And while working on stuff you always try to find the best possible outcomes (that's why you do the research in the first place)

If it weren't it would make no sense to arbitrarily choose 60C (which is, after all, not the most common ambient temperature for storing batteries). If they wanted to show worst case scenarios they'd have gone to freezing temperatures or excessively high temperatures.

If that value is somewhre in the 150k-200k range then that's OK because most cars don't last that long.

I dunno. That's still pretty weak, considering that the average age of cars is around 10-12 years almost everywhere, so if it only does 150,000 kilometers then it won't last the entire life of the car. Most cars do remain in use for 20 odd years, and are expected to go about twice that, so having a car that needs a major overhaul like a whole new battery pack at 150k doesn't really cut it in comparison.

This is something I learned reading/writing papers: Anything not explicitly stated in the paper should notbe inferred.

A news article is not a paper.

If they wanted to show worst case scenarios they'd have gone to freezing temperatures or excessively high temperatures.

60 C is rather excessive for lithium batteries. 40 C is enough to lose you up to 25% capacity in a year. Freezing temperatures don't wear them out, they just reduce the available power.

I mean, something like a Volkswagen Golf GTi in a good condition can still sell for €10.000 after 200.000 km. It's not the kilometers, because the engine will take half a million easily, but how you've kept the rest of the car.

The same cannot be said of electric cars, where you need to plonk down €10.000 for a new battery just to make it run, so the resale value of the car cannot be more than a few hundred euros.

That's why it's important that both the shelf-life and the cycle life of the battery extend well beyond the 150k/10 year mark. Otherwise you can't recover any of the costs by selling the car and you end up paying more than you'd pay for a comparable vehicle that runs on gasoline.

Golf GTi in a good condition can still sell for €10.000 after 200.000 km

After 200k km no car is in 'good condition'. I just checked a few listings - the average price of a Gti with that kind of mileage is below 1000 Euros (mostly even below 500 Euros). After that kind of use you're not going to recover diddly squat from a car.

But I think I'll start up an export business to the US if that's the kind of prices they're willing to pay for these kinds of cars. The profit margins would be astronomical.

Figure S1, coulombic efficiency over cycle number at room temperature and 60 C.

They're both essentially the same, which means 60 C is not the "optimal" temperature for this battery.

What is alarming though is that the capacity of the battery falls so dramatically even with 1/10 C discharge rates, which means that it really doesn't like to be charged or discharged quickly. At that rate, an 85 kWh battery pack can deliver only 8.5 kW (12 HP) of power which makes it really unsuitable for electric vehicles.

I beg to differ. It just depends on whether you've actually maintained your car properly. It's not 1970 anymore when you'd expect to have the U-joints fall off every 50.000 kilometers. Keep to the maintenance schedule, and the car will be almost good as new at 150k.

And the majority of second hand cars on sale are crash vechicles and other "jobs" imported from Romania or somesuch, that fetch a low price because there's such an over-abundance of them and people don't trust that they're any good.

Of course there's going to be more bad cars on the market than good cars, because people don't buy the 1000 euro botch-jobs.

Sulfur batteries? that could be useful for powering shark-mounted "lasers", if one were so inclined. Sounds like a plan for a business partnership with some infernal investors. Brimstone Batteries has a not-so-nice ring to it, doesn't it?

[Eikka]What is alarming though is that the capacity of the battery falls so dramatically even with 1/10 C discharge rates, which means that it really doesn't like to be charged or discharged quickly. At that rate, an 85 kWh battery pack can deliver only 8.5 kW (12 HP) of power which makes it really unsuitable for electric vehicles.

That's what I was wondering about. Looks like a great battery for energy density, but not that great for power density. And it will still take a long long time to charge, compared to pumping gasoline into a car. Sounds great for small scale stuff, though.

"This is something I learned reading/writing papers: Anything not explicitly stated in the paper should notbe inferred. I'd wager that the 60C is the optimal temperature for maximizing recharge cycles. They want to show how good the battery is - not how bad."

Speaking as someone who used to develop and test technology, I can assure you that this isn't the case. When you test something in the lab, you want to find where it fails, because that's where you can improve things. Testing in best case conditions just opens you up for disappointment later when it your device, program, whatever... fails in the field.

Of course, if you are more interested in good press than good products, quoting optimal performance is the way to go.

Grallen wrote, "I like the fact that this has been developed by a government lab, meaning no patent gouging."

Read the article.

The lab is applying for a patent. They will then license the technology. The manufacturers who license the technology will be able to sell to a non-free market, where those without a license are not able to compete.

It's business as usual in America, where monopolists always get a helping hand from government.

I like the fact that this has been developed by a government lab, meaning no patent gouging...........except that this will likely be quickly picked up by the Chinese.

Why is that bad? The Chinese are major polluters. If we can solve the energy storage problem, they can make more shifts to renewables. We don't have to trample on everyone else to make the world better for ourselves. I think we should give away these things if they work.

This means the Tesla car can go a heck of a lot faster and a helluva lot farther on less battery weight... Yes! Facetious, but an electric car battery system of this type will be cheaper, faster, safer, more efficient, last longer, and run longer at the same loads. Can also permit more powerful electric motors.

My wife's last vehicle went over 150K miles (~241k km) before my older son totaled it. My last 2 vehicles both went over 200K miles (~322k km). The first one I gave to charity as it needed a new AC compressor and I was ready for a new car, I gave the second car to my younger kid to drive to school and around town after I bought another new one. While neither of those 200K mile cars would qualify for the "good condition" rating, they both have good powertrains and suspensions and are reliable transportation. When I was poor, vehicles like these were top notch compared to what I was driving. I think EVs with improved range and battery life is a great step, however, the poor depend upon a supply of reliable older cars that can be repaired with minimal cost. Hopefully, this battery tech can reduce the cost so that we don't leave the poor without a source of reliable used cars that are affordable to repair.

The lab is applying for a patent. They will then license the technology. The manufacturers who license the technology will be able to sell to a non-free market, where those without a license are not able to compete.

It's business as usual in America, where monopolists always get a helping hand from government.

In the 1990's US monopolists were awarded billions in patent infringement cases against Japanese companies that stole technology by recruiting disgruntled employees.

Taking a page from the kings of corporate scum, modern patent pillaging shops in Asia structure record keeping and cash operations for virtual immunity from prosecution.

As more Western R&D investors respond by refusing to publish patents in public domains, Asia has stepped up computer hacking efforts to access in-house corporate research.

Obama is now being pressured by corporate America to address these cyber attacks, which they say makes normal operation of their business impossible.

The lab is applying for a patent. They will then license the technology. The manufacturers who license the technology will be able to sell to a non-free market, where those without a license are not able to compete.

It's business as usual in America, where monopolists always get a helping hand from government.

In the 1990's US monopolists were awarded billions in patent infringement cases against Japanese companies that stole technology by recruiting disgruntled employees.

Taking a page from the kings of corporate scum, modern patent pillaging shops in Asia structure record keeping and cash operations for virtual immunity from prosecution.

As more Western R&D investors respond by refusing to publish patents in public domains, Asia has stepped up computer hacking efforts to access in-house corporate research.

Obama is now being pressured by corporate America to address these cyber attacks, which they say makes normal operation of their business impossible.

At half the voltage of Li-ion cells these might be useful as a alternative to NiMH batteries. I think a application in a small sized product with a potentially very high volume market would be a logical first for commercialization. I think everyone is getting ahead of themselves thinking of going right to the most demanding of applications for this new tech.

I have a 1993 Ford Escort, 160 000 Km, I can sell it to you for 10 000 € !

If it was a 2003 Ford Escort with 160k on the meter, and it had a spotless service history, then I could see it approaching those figures. 2003 Escorts with 100 000 miles on the clock are worth about $5000 - $8000 in good condition. Newer cars, despite being driven a lot, fetch a lot more than old cars that have seen many winters and have leaky bits and rust spots, and generally need more upkeep.

The point is that AntiAlias thinks any car that's gone over 150...200 000 km is totally worthless, which isn't true. It's not really the kilometers that ruin a car, but how you maintain and keep it.

Maybe in Germany there's just a glut of second hand cars being dumped on the market that drives the price down. Elsewhere a fairly recent model car with 150 00 km is basically just been "ran in".

The point is that AntiAlias thinks any car that's gone over 150...200 000 km is totally worthless,

No. What I SAID was that there is no way in hell a GTI (which is a smallish car) that has 200k km on the clock is going to sell for 10k$.AND what I said was that no car is in prime condition after 200k km. Your gerabox has wear and tear. Your motor has wear and tear. The friggin seats have wear and tear. And unless you invest 5-6k into replacements you're not going to sell it for 10k. No way no how.

The authors keep talking about the cathode, but they do not reveal what the energy density is for the whole battery. My guess is that the anode was very heavy and that the overall energy density was unimpressive. Finding a better one is probably not that easy.

I am also dissapointed that they stopped their cycling after 300 cycles. This is - just as Eikka pointed out - far lower that what is needed. A lithium iron sulfide battery that costs three times the sulfur battery per kWh can still be cheaper overall due to it's 1000 cycles.

Yes, I too like this research but let's not go overboard eh? Until someone in the manufacturing sector picks it up it will remain research and that's a shame. There is one ray of hope though; being government research perhaps the military may be able to develop it. Or perhaps try it out on the Golf Course.There are some good points posted about the cars in general but I think location is an important factor. Where I live large volumes of dust and poor roads can make a new car an old one very quickly, that is mechanically speaking.Then there is the other extreme where roads have to be continually treated due to low temp conditions which also can have an effect on the life span.In other words car structure will tend to fall apart before the engine does.Also depends on the 'make' one would expect a longer life from a more expensive car than a cheaper one. I'm sure the car industry has stats on this and could decide.

Your gerabox has wear and tear. Your motor has wear and tear. The friggin seats have wear and tear. And unless you invest 5-6k into replacements you're not going to sell it for 10k. No way no how.

The engine and gearbox are easily good up to half a million kilometers in modern cars, so they're nowhere near as bad as you make it sound - assuming the car wasn't ruined by a teenager. The drivetrain is the last to go in most old cars - it's usually the body and suspension that gives in before the engine does, and most old cars fail inspections on things like rusted doors.

The upholstery is a secondary issue, but usually, unless it's leather seats - it's just fine in cars that are less than ten years old. You spend relatively little time actually sitting in your car, rather than the car sitting on a parking lot empty.

What you do have to look for is suspension, brakes, and engine belts. Those are about €500 maximum in parts and work, and they start to fail at the 150k mark.

Very many cars are in good condition after 200 Mm, and many of them sell for much more than a thousand euros. What you see listed online is just the cars that are in bad condition, that people won't buy because they are in bad condition, whereas the good cars don't show up because someone already bought them.

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